S690QL and S620QL are both high-strength, quenched & tempered (Q&T) structural steels under EN 10025-6, but the main difference lies in their specified minimum yield strength: S690QL has a higher minimum yield of 690 MPa, while S620QL has a minimum yield of 620 MPa, making S690QL stronger, with S690QL also typically offering better low-temperature toughness (QL for Low Temperature) for critical applications, though both use QL suffix for Q&T.
Chemical Composition
|
S620QL Chemical Composition |
||||||||
|
Grade |
The Element Max (%) |
|||||||
|
C |
Si |
Mn |
P |
S |
N |
B |
Cr |
|
|
S620 QL |
0.20 |
0.80 |
1.70 |
0.020-0.025 |
0.010-0.015 |
0.015 |
0.005 |
1.50 |
|
Cu |
Mo |
Nb |
Ni |
Ti |
V |
Zr |
|
|
|
0.50 |
0.70 |
0.06 |
2.0 |
0.05 |
0.12 |
0.15 |
|
|
|
S690QL Chemical Composition |
| C | Si | Mn | Ni | P | S | Cr | Mo | V | N | Nb | Ti | Cu | Zr | B | CEV |
| max 0.2 | max 0.8 | max 1.7 | max 2 | max 0.02 | max 0.01 | max 1.5 | max 0.7 | max 0.12 | max 0.015 | max 0.06 | max 0.05 | max 0.5 | max 0.15 | max 0.005 | max 0.83 |
Mechanical Property
|
Grade |
S620QL Mechanical Property |
|||||
|
Thickness |
Yield |
Tensile |
Elongation |
Min Impact Energy
|
||
|
S620 QL |
mm |
Min Mpa |
Mpa |
Min % |
-40 |
30J |
|
3<t≦50 |
620 |
700-890 |
15 |
-40 |
30J |
|
|
50<t≦100 |
580 |
700-890 |
15 |
-40 |
30J |
|
|
100<t≦150 |
560 |
650-830 |
15 |
-40 |
30J |
|
S690QL Mechanical Property
| Nominal thickness (mm): | 3 - 50 | 50 - 100 | 100 - 150 |
| Rm - Tensile strength (MPa) | 770-940 | 760-930 | 710-900 |
| Nominal thickness (mm): | 3 - 50 | 50 - 100 | 100 - 150 |
| ReH - Minimum yield strength (MPa) | 690 | 650 | 630 |
| KV - Impact energy (J) longitud., | 0° 50 |
-20° 40 |
-40° 30 |
| A - Min. elongation Lo = 5,65 √ So (%) | 14 |
S690QL
Strength: Higher strength, minimum yield strength of 690 MPa.
Application: Used for heavy-duty structures needing excellent strength-to-weight ratios, like cranes, bridges, and heavy machinery.
Toughness: Often tested to higher impact energy standards (like 40J at -20°C or -40°C) due to the 'QL' (Quenched & Tempered, Low Temp) designation, suitable for very cold environments.
S620QL
Strength: Still high strength, but lower than S690QL, with a minimum yield strength of 620 MPa.
Application: Also for high-yield applications, but where slightly less strength than S690QL is sufficient.
Toughness: Also benefits from Q&T (QL), offering good impact properties, but its baseline yield is lower.
